TAC1 and Headache: Besides containing noradrenaline, LC neurons also co‐express other neuropeptides known to be involved in headache are also expressed in the LC, including pituitary adenylate cyclase‐activating peptide, substance P, and neuropeptide Y, etc.12, 21, 22, 23, 24Stress and emotional factors are known triggers for both pain and headache, and the LC is a key mediator of the stress response.